New In Vitro Methodology for Kinetics Distribution Prediction in the Brain. An Additional Step towards an Animal-Free Approach

Establishment and Validation of a New Co-Culture for the Evaluation of the Permeability through the Blood-Brain Barrier in Patients with Glioblastoma

Currently, the mechanisms involved in drug access to the central nervous system (CNS) are not completely elucidated, and research efforts to understand the behaviour of the therapeutic agents to access the blood-brain barrier continue with the utmost importance. The aim of this work was the creation and validation of a new in vitro model capable of predicting the in vivo permeability across the blood-brain barrier in the presence of glioblastoma. The selected in vitro method was a cell co-culture model of epithelial cell lines (MDCK and MDCK-MDR1) with a glioblastoma cell line (U87-MG). Several drugs were tested (letrozole, gemcitabine, methotrexate and ganciclovir). Comparison of the proposed in vitro model, MDCK and MDCK-MDR1 co-cultured with U87-MG, and in vivo studies showed a great predictability for each cell line, with R2 values of 0.8917 and 0.8296, respectively. Therefore, both cells lines (MDCK and MDCK-MDR1) are valid for predicting the access of drugs to the CNS in the presence of glioblastoma.

Exploring a Bioequivalence Failure for Silodosin Products Due to Disintegrant Excipients

Some years ago, excipients were considered inert substances irrelevant in the absorption process. However, years of study have demonstrated that this belief is not always true. In this study, the reasons for a bioequivalence failure between two formulations of silodosin are investigated. Silodosin is a class III drug according to the Biopharmaceutics Classification System, which has been experimentally proven by means of solubility and permeability experiments. Dissolution tests have been performed to identify conditions concordant with the non-bioequivalent result obtained from the human bioequivalence study and it has been observed that paddles at 50 rpm are able to detect inconsistent differences between formulations at pH 4.5 and pH 6.8 (which baskets at 100 rpm are not able to do), whereas the GIS detects differences at the acidic pH of the stomach. It has also been observed that the differences in excipients between products did not affect the disintegration process, but disintegrants did alter the permeability of silodosin through the gastrointestinal barrier. Crospovidone and povidone, both derivatives of PVP, are used as disintegrants in the test product, instead of the pregelatinized corn starch used in the reference product. Permeability experiments show that PVP increases the absorption of silodosin-an increase that would explain the greater C_max observed for the test product in the bioequivalence study.